Hollow propeller



Aug. 21, 1945. w. H. RILEY 2,383,342

' HoLLow VPROPELLER f Filed Oct. 21'. 1941 3 sheetsheet. 1

Aug. 21, 1945. `w. H. RILEY 2,333,342

' v HoLLow 1= RoPELLER File@ oct. 21', 1941 v.s sheets-sheet 2 Aug. 21, 1945. w. H. RILEY h 2,383,342

HOLLOW PROPELLER Filed oct. 21, 1941 s sheets-sheet s Patented Aug.4 2 1, 1945 UNITED STATES PATENT `OFFICE noLLow PaorELLnn William Il. Riley, Pittsburgh, Pa. Application october 21, 1941, sei-n1 No. 415,980 1 claim. (c1. 17o- 459il Ilhis invention is an airplane propeller, particularly designed for lightness. strength and quantity production.

The body of the propelleris essentially a iiattened hollow tube, the topand bottom walls o1 the tube preferably being formed integrally with gently curved leading and trailing portions,

. whereby no sharp angles or corners are presented. Such a tubular construction is stronger, weight for weight, than a blade made of solid metal. Furthermore, the elimination of sharp angles and corners greatly strengthens the tube.

In actual practice, with sharpcorners or angles, vibration and mechanical stresses tend to be concentrated at such angles or corners, 'with resultant failure of the propeller at these points.

'statically bonded to the hollow tubular core or body portion. Once the proper dies are made for the bonding operation, the airfoil contour of the blade may be rapidly and accurately completed by bonding the plastic material to the metallic core for giving a. finished propeller 'of correct airfoil contour.

The supplementary body portion, in addition to its primary function .of completing the correct airfoil contour, also materially strengthens the blade and under certain conditions presents a better surface to wear by abrasion than metal.

In one aspect of the invention, the major portion of the attened metallic tubular core is exposed, the supplementary body portions of plastic material being bonded to the core for forming the leading and trailing edges of the blade.

In another aspect of the invention, the supplementary body, portions cf plastic material, in addition to forming the leading and trailing edges of the blade may completely cover the metallic core. Also, if desired, the plastic portion additionally may cover only one surface of the blade, leaving the other surface exposed, or may be used in the most advantageous manner to obtain the desired airfoil contour.

A further feature of the invention is that the leading edge, or the trailing edge, or both, oi the metallic body portion, may be strengthened such edge or edges. This additional metal may be in the form of a thickened leading or trailing edge, or in the form of a flange extending l outwardly and forwardly froml the leading edge, or extending outwardly and rearwardly from the illustrating in more detail the described construction.

In these drawings: I

Figure 1 is a plan view of an airplane blade inv accordance with the present invention.

Fig-ure 2 is a cross section taken on'the line 2--2 of Figure 1.

Figures 3 and 4 are cross sections taken on approximately lines 3-3 and 4-4 of Figure 1. Figure 5 is a plan view of another embodiment of the invention.

Figures 6, I and 8 are cross sections taken on 'Ihe stream-lined contour is" approximately lines 6 6, 1--1 and 8-3 of Fig. 5.

Figure 9 is a cross section of a modified blade where the top of the metallic body portion is exposed.

Figure 10 is a cross section oi.' a modified blade where the bottom of the metallic body portion is exposed.

Figure 11 is a cross section of a modification where the leading and trailing edges of the metallic body portion are strengthened by ilanges. Figure 12 is a cross section of a modification where the trailing edge of the body portion is strengthened and completed by a weld.

Figure 13 is a. cross section of a modification t where the leading and trailing edge of the metalby the use of additional metal extending along 66 lic body portion are strengthened by thickened walls. l

Figure 14 is a cross section of a modification where the trailing edge is strengthened bythe use ot an attached ilange.

Figs. 15 and 16 are cross sectional views of modiilcations similar to Figs. 9 and 10, wherein the trailing edges o! the metal body are strengthened by additional metal.

`Referring now to thesedrawings in which similar reference characters represent similar parts, the main body portion 2 of the blade is of metallic flattened tubular construction, having an upby a. supplementary body portion comprising a leading edge i2 and a trailing edge I4, made of some suitable thermoplastic material which is thermostatically bonded to the metallic core,

the preferred material being vulcanized rubber. Other suitable plastics, however, such as vulcanized ilber could be used.

With this form of the invention, most of the metallic body portion is exposed, the leading and trailing edges of the core being covered by the plastic leading and trailing edges i2 and I4.

In the form of the invention shown in Figures 5 to 8, the metallic body portion is of substantially the same shape and material as shown in the earlier nguresand corresponding parts are similarly numbered. In this form of the invention, however, the supplementary body portion comprisesa leading edge 20, a trailing edge 22, an upper covering 24 and a lower covering 28. The portions 20, 22, 24 and 28 of the supplementary body portion are of thermoplastic material thermoplastically bonded throughout to the metallic core and completely covering it.

In the form of inventiono shown in Figure 9, the metallic body portion 4 is provided with a supplementary plastic body portion, indicated generally at 30, for completing the airfoil contour. the plastic including a portion 3l covering the bottom or thrust side of the blade, leaving the other or top side exposed. The leading edge is strengthened by additional metal 34.

In the form shown in Fig. 10 the metallic body portion 4 has itsair foil contour completed by a supplementary plastic body portion 32 bonded to the metal, the plastic coveringthe top of the blade and leaving the bottom or thrust side exposed. The leading edge is vstrengthened by additional metal 34.

In the form of invention shown in Fig. 11, the metallic body portion 4a is strengthened by the use of additional metal in the form of a for-` wardly and outwardly extending thick flange 34 at the leading edge, and by the use of a rearwardly and outwardly extending` somewhat thinner flange 38 at the trailing edge. The airi'oil contour is completed as before by the use of plastic material 31 bonded to the metal and I completely enclosing flanges 34 and 36.

In the form of invention shown in Fig. 12,

the metallic body portion 4b is strengthened by' the use of additional metal in the'form of a welded insert'or fillet 38, the airloil contour being completed by the plastic, supplementary body portionA 40 bonded to the metal.

In the formof invention shown in Fig. 13, the metallic body portion 4c is strengthened by 'the use of additionalmetal in the form of a thickened wall 42 at the leading edge and a thickened wall 44 at the trailing edge, the airfoil contour being completed as before by a supplementary plastic body portion 46 bonded to the metal.

In the form of invention shown in Fig. 14, the metallic body portion 4d Ihas its trailing edge strengthened by the use of a ilange 48 having branches 49 extending upwardly and downwardly and welded to the trailing edge. The leading edge could be strengthened vby a similar flange or by an integrally formed reinforcement as in Fig. 1 1 or 13 for example.

With the severalforms of the invention as described in Figs. l1 to 14, the supplementary plastic body portion could completely enclose the metallic body portion. or one side or the other of the metallic body portion could be exposed, as in Fig. 9 ory Fig. 10.

In Fig. 15, the thrust side of the blade is exposed, as in Fig. 10, and the metal body is 'strengthened by additional metal 36 at the trailing edge. In Fig. 16, the top or suction side of the7 blade is exposed, as in Fig. 9, and the metal body is strengthened by addition-al metal 44 at the trailing edge. l

There is thus provided a composite propeller comprising a flattened tubular metallic core which presents maximum strength for the amount of metal used by virtue of the tubular other ways as falling within the scope of the following claim.

I claim as my invention: An airplane propeller blade comprisingv a hollow metallic body portion of flattened, tubular shape, extending the vfull length of the blade. one of the edges of such body portion being reenforced and strengthened by additional metal y at such edge, and a supplementary body portion of plastic material thermoplastically bonded to only one side of the blade, leaving the opposite metallic side of the body portion exposed, said supplementary plastic body portion being substantially thickened at its leading and trailing edges and5 extending for the full length of the blade, and serving to complete the airfoil contour thereof.

WILLIAM H. RILEY. 

